Automotive headlight dimming system



Oct 195-1 1.. A. VANDERLIP AUTOMOTIVE HEADLIGHT DIMMING SYSTEM FiledOct. 24, 1949 IN VEN TOR.

Patented Oct. 30, 1951 AUTOMOTIVE HEADLIGHT DIMMING SYSTEM Laurence A.Vanderlip, Wichita, Kans. Application October 24, 1949, Serial No.123,221

1 Claim. 1

This invention relates to a control system, particularly adapted for usewith automobiles, and operable automatically to dim the headlightsthereof upon approach of another lighted vehicle, and to restore theheadlights to a bright condition immediately after passing, all withoutoperator attention of any kind.

The primary object Of this invention is to provide an automaticheadlight control that is easily and simply installed and coupled withexisting automobile electric circuits without substantial variation andwithout affecting adversely the operation thereof in any manner.

The most important object of the present invention is to provide acontrol that can-be installed, and subsequently be selectively placed inuse or rendered inoperable by the operator by the mere manipulation of aswitch arm or button, which operator action also renders the existingmanual dimming apparatus of the automobile inoperable while the controlhereof functions.

Another important object is to provide a photoelectric control that ishighly sensitive to rays of light and provided with minute adjustingmeans, making it possible for the-user to determine the intensity oflight necessary to render the dimming operation operable.

Other objects include the way a control vacuum tube is utilized tonormally maintain an electric make and break mechanism open, the way inwhich current flow in the tube controls said mechanism; the manner ofcoupling a photoelectric cell with the tube to control the samedepending on variance in light rays falling on the tube; and the mannerof maintaining a constant voltage on the cell and the control tuberegardless of load variation and other factors effecting the currentsource.

More minor objects will be made clear or become apparent as thefollowing specification proceeds, reference being had to theaccompanying drawing, wherein the single figure is a schematic wiringdiagram showing an automobile headlight dimming system made inaccordance with my present invention.

A pair of automobile headlights l and I2 are provided with incandescentlamps l4 and I6 respectively. Lamp I4 is provided with a bright filamentl8 and a dim filament 20; likewise lamp [6 has a bright filament 22 anda dim filament 2 24. A battery 26 grounded at 28 supplies electricalenergy for lamps l4 and i6 through an ammeter 30 and a-main switch 32.

A manual switch 34 couples bright filaments l8 and 22 with battery 26when closed with respect to contact 36 and couples dim filaments and 24with battery when closed with contact 38. This operation takes placeonly when switch 32 is closed and when a switch 40 interposed betweenswitches 32 and 34 is in engagement with a fixed contact 42.

Battery 28 supplies electrical energy to the automatic control formingthe subject matter of this invention when'a switch 44 (ganged withswitch 46 for manual operation therewith) is closed with respect to astationary contact 46. When switch at is in such position, switch 46 isin a closed relationship with a contact 48, rendering switch 34ineffectual.

A switch arm 5%, normally held biased against a contact 52 by a spring54, is connected with the battery 26 when the switch 46 and the contactpoint 46 are interengaged. Contact point 52 is coupled directly withbright filaments I8 and 22 while an opposed stationary contact point 56is in connection with dim filaments 20 and 24.

A relay 58 grounded at 66, i disposed relative to metallic switch arm toattract the latter upon energization of relay 58, thereby deenergizingbright filaments I8 and 22 and energizing dim filaments 26 and 24(provided switch 32 is closed and switches 46 and 44 are closed withcontacts 48 and 46 respectively), because of movement of arm 50 againstthe action of spring 54 from contact 52 to contact 56. Energization ofrelay 58 to automatically dim headlights Ill and [2, takes place uponmovement of a contact arm 62 from the normally open position shown to aclosed position in engagement with'a stationary contact 64. This closesthe following circuit through relay 58, energizing the coil thereof andattracting arm 50 toward contact 56. I

From battery 26, through ammeter 30, closed switch 32, switch arm 44,contact 46, wires 66, 68 and 10, switch arm 62, contact 64, 'wire 12,relay 58, and wire 14 to ground 66.

The contact arm 62 is normally held out of engagement with thestationary contact 64 by a relay 14 that operates when energized, toattract arm 62 against a spring 16.

In order to convert light waves or energy, emanating from an approachingautomobile, into electrical current or energy, there is provided aphotoelectric tube I8. The circuit for energizing the relay I4 iscontrolled by the intensity of light entering the tube 18 and fallingupon a light sensitive element or cathode 80, forming a part of tube 18,through use of suitable photoelectric materials in the usual manner.

A triode vacuum tube 82, provided with a cathode 84 having a filament86, a control grid 88, and a plate or anode 90, has its grid 88 coupleddirectly with anode 92 of photoelectric tube I8 by a wire 94.-Obviously, the operation of tube 82 depends upon the number ofphotoelectrons I discharged by tube I8, and similarly, the emission ofelectrons by tube I8 is dependent upon the intensity *of light fallingupon. cathode 80.

The brighter the light entering tube I8, the greater the current outputthereof.

Heating of filament 86 of tube 82 is by direct" current through thefollowing circuit: 7

From battery 26, through ammeter 30, closed switch 32, switch arm 44,contact 46, wires 66, 68 and 96, and filament'86 to ground 98.

Plate 90 of tube 82 is positively charged by connection with one side ofthesecondary- I00 of a power transformer I02 through lines I04, I06 andI08, there being a resistor III} coupled in this circuit to operate asavoltage compensator.

Transformer I 02 receives energy from battery 26 through a directconnection with one side of its primary I09 by line I I I with wire 66.A transformer type vibrator I I3 of conventional character, connectswith the opposite sides of windings I 00 and I09.

It is seen therefore, that relay I4 operates in response to the platecircuit of tube 82 since one side of its coil is connected with wire I64of plate 90 through wires [I2 and H4 and the other side of its coil hasconnection with cathode 84 of tube 82 by wire I I6. Thus with apredetermined plate current flow, relay I4 will normally remainenergized to hold arm 62 in the open position shown against the bias ofspring I6.

Accordingly, since a variance in voltages fed into grid 88, controls thecurrent flowing in the plate circuit of tube 82, variance in the photo-'electron emission of anode 92 will control relay I4.

Tube I8 receives energy from secondary I00 of transformer I02 to whichit is connected by a circuit including a wire II8 joined with its lightsensitive cathode 80.

The voltages supplied to tubes 18 and 82 are maintained constantregardless of each variation, and are thereby controlled and fed properoperating voltages by a pair of voltage regulator tubes I20 and I22respectively, and the voltages applied to tube I8 is additionallycontrolled by a manually operable, variable resistor I24, all interposedwithin the supply line I08 of secondary I00.

Consequently, with the proper selection of tubes I20 and I22, andselected setting of resistor I 24, tube 82 can be caused to normallyoperate, as above set forth, in maintaining relay I4 energized. The gridreturn 94 for tube 82 is connected with cathode 84 in the usual mannerthrough a bias resistor I26 and a by-pass condenser I28.

Accordingly, during normal operation, tube I22 will permit tube 82 to besupplied with suflicient voltages to maintain relay 14' energized. .The

'plate current of tube 82 will not be effected by 4 the negative chargeon grid 88 to the extent of preventing sufiicient current flow in theplate circuit of tube 82 for supplying relay I4 with enough energy toovercome the tension of spring I6.

However, tube I20 will supply tube I8 with suflicient energy to increasethe negative charge on grid 88 when an outside light source falls oncathode 80 and the intensity of such light necessary to overcome springI6 will depend on the position of resistance I24. In other words, byprecise adjustment of resistor I24, the user can predetermine withminute accuracy the intensity of light necessary to cause closing ofrelay I4.

Obviously, the sensitivity control resistance I24 should be set to causea strong negative bias on grid 88 when exceptionally bright light raysare directed to tube I8, and to also assure that the increase in outputof tube I8, in case of dim lights, will not be suflicient to causeclosing of switch arm 62.

It is seen therefore, that when tube I8 is placed on an automobile whereits cathode 88 will intercept rays of light from another oncomingautomobile, dim filaments 20 and 24 will become automatically energizedin lieu of bright filaments I8 and 22.

If, under test, it is determined that the circuit is too sensitive,responding to approaching automobiles at a long distance, thenresistance I24 can be adjusted to require light of greater intensity todecrease the plate current of tube 82. These adjustments can also bemade when bright moonlight, street lights or stop lights eifect thecontrol in an undesirable manner. And, if desired, means could beprovided to shade tube 78 in a manner to prevent rays of light emanatingfrom the sides, above or below tube I8 from effecting the same to anyappreciable extent.

While I have shown and described a particular embodiment of theinvention, it will be apparent to those skilled in the art that numerousmodifications and variations thereof may be made without departing fromthe underlying principles of the invention. I, therefore, desire, by thefollowing claim, to include within the scope of my invention, all suchmodifications and variations by which substantially the results of theinvention may be obtained by the use of the same or equivalent means.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

In a lighting system, a dim circuit and a bright circuit; a first switchcommon to said circuits and movable to and from positions alternatelyclosing the same; a source of electrical energy; a relay having make andbreak mechanism; a second switch movable to and from positionsalternately coupling said first switch and said mechanism with saidsource, said mechanism normally closing said bright circuit when coupledwith said source, said relay having a coil for moving said mechanism toa position opening the bright circuit and closing said dim circuit whensaid coil is energized; an operating circuit for the coil; an electronictube having a control grid and an anode-cathode circuit; a second relayhaving an operating coil in said anode-cathode circuit and a switch insaid operating circuit; voltage control means in said anode-cathodecircuit for maintaining said operating coil energized to hold saidswitch normally open; electrical apparatus coupled with said controlgrid for receiving and converting rays of light into electrical energy;a circuit for said apparatus; means in said last mentioned circuit fornormally controlling the voltage from said apparatus to said controlgrid; a variable resistor in said last mentioned circuit for controllingthe emission of electrons by said apparatus whereby to deenergize saidanode-cathode circuit only upon light of predetermined intensity passingto said apparatus; and a third switch ganged for movement with saidsecond switch to a position for coupling said source with the operatingcircuit, the anode-cathode circuit and the circuit for said apparatuswhen the second switch is moved to a position coupling said mechanismwith the source of energy.

LAURENCE A. VANDERLIP.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,150,900 Alley Mar. 21, 19392,219,976 Berg, Jr. Oct. 29, 1940 2,380,486 Willis July 31, 19452,431,394 Friedman Nov. 25, 1947 2,476,389 Schmidt, Jr. July 19, 19492,493,307 Moore et al. Jan. 3, 1950

